This invention relates in general to methods for forming joints between metallic components, such as a joint between a pair of metallic structural components for use in a vehicular body and frame assembly. In particular, this invention relates to an improved method for permanently joining such a pair of metallic structural components using magnetic pulse welding techniques.
Many land vehicles in common use, such as automobiles, vans, and trucks, include a body and frame assembly that is supported upon a plurality of ground-engaging wheels by a resilient suspension system. The structures of known body and frame assemblies can be divided into two general categories, namely, separate and unitized. In a typical separate body and frame assembly, the structural components of the body portion and the frame portion of the vehicle are separate and independent from one another. When assembled, the frame portion of the assembly is resiliently supported upon the vehicle wheels by the suspension system and serves as a platform upon which the body portion of the assembly and other components of the vehicle can be mounted. Separate body and frame assemblies of this general type are found in most older vehicles, but remain in common use today for many relatively large or specialized use modern vehicles, such as large vans, sport utility vehicles, and trucks. In a typical unitized body and frame assembly, the structural components of the body portion and the frame portion are combined into an integral unit that is resiliently supported upon the vehicle wheels by the suspension system. Unitized body and frame assemblies of this general type are found in many relatively small modem vehicles, such as automobiles and minivans.
Traditionally, the structural components of such vehicular body and frame assemblies have been formed exclusively from steel alloys. Steel alloys are relatively high strength materials, and it is relatively easy to permanently join steel alloy structural components using traditional welding techniques, such as gas metal arc welding. Unfortunately, steel alloys are also relatively heavy materials. Thus, there has been a movement to form some or all of the structural components of these vehicular body and frame assemblies from lighter weight materials, such as aluminum alloys. Such aluminum alloys and other materials are both strong and lightweight and, therefore, are usually regarded as desirable substitutes for steel alloys in vehicular body and frame assemblies. However, it has been found to be relatively difficult to permanently join such structural components using traditional welding techniques.
Magnetic pulse welding is a well known process that can be used to permanently join two metallic components, such as a pair of metallic structural components for a vehicular body and frame assembly. Magnetic pulse welding is particularly advantageous because it can readily and permanently join components that are formed from different metallic materials. Typically, a magnetic pulse welding process is performed by initially disposing the end portions of first and second metallic components in a concentric, axially overlapping relationship. An electromagnetic inductor or coil is provided for generating an intense magnetic field either within or about the axially overlapping portions of the first and second metallic components. When this occurs, a large pressure is exerted on one of the first and second metallic components, causing it to move toward the other of the first and second metallic components at a high velocity. If the electromagnetic inductor is disposed about the exterior of the two metallic components, then the outer metallic component is deformed inwardly into engagement with the inner metallic component. If, on the other hand, the electromagnetic inductor is disposed within the interior of the two metallic components, then the inner metallic component is deformed outwardly into engagement with the outer metallic component. In either event, the high velocity impact of the first and second metallic components cause them to become permanently joined or welded.
In order to facilitate the performance of the magnetic pulse welding process, it is usually desirable to orient the overlapping end portions of first and second metallic components at a predetermined angle relative to one another (i.e., not parallel to one another). This predetermined angle of orientation, as well as other parameters of the magnetic pulse welding process, will vary with the sizes, shapes, materials, and other characteristics of the two metallic components to be joined together. Thus, it would be desirable to provide an improved method for permanently joining a pair of metallic components, such as a pair of metallic structural components for use in a vehicular body and frame assembly, that orients the overlapping end portions of the first and second metallic components at this predetermined angle relative to one another to facilitate the performance of the magnetic pulse welding process.